1. Field of the Invention
This invention relates to a firearm comprising a gas drive for actuating loading and/or firing means in response to the discharge of a round, wherein the gas drive comprises a pneumatic cylinder and a pneumatic piston, the cylinder chamber communicates with the barrel bore through at least one transverse bore in the barrel, and powder gas is adapted to enter said cylinder chamber through said transverse bore and to move said cylinder and piston relative to each other against the force of a return spring.
2. Description of the Prior Art
For a semi-automatic or fully automatic operation of a firearm, drive means must be provided for the performance of individual steps of the loading and ejecting operation or for the entire loading and priming operation. Gas drives in which the residual energy contained in the powder gases when the round has been discharged have proved satisfactory as drive means. The previous gas drives consist of piston-cylinder units which are separate from the barrel and their cylinders have rigidly been connected to the barrel or to the housing and the reciprocating piston is moved to actuate the corresponding members of the loading and/or firing mechanism by means of a piston rod or the like. As such piston-cylinder units consist of a substantial number of expensive components they involve a substantial structural expenditure and occupy a large valuable space and also add to the weight of the firearm.